iPhone 5C Ramp-Up Raises Costs

Pegatron Corp. booked record third-quarter revenue on Monday, buoyed by orders for the iPhone 5C as it became the primary supplier of the smartphone for the first time. Its profit margins were squeezed, however, weighed down by costs for the rapid ramp-up in production.

The earnings result suggests what could be in store for other assemblers next year, as Apple...